The present invention generally relates to air conditioning apparatus and, in a preferred embodiment thereof, more particularly relates to a specially designed refrigerant gauge manifold having a built-in refrigerant charging calculator.
As is well known in the air conditioning industry, for an air conditioning system to properly perform at its designed-for capacity the charge level of its refrigerant circuit must be neither too high nor too low. It is accordingly desirable to periodically check the amount of refrigerant which the refrigerant circuit contains. In direct expansion type refrigerant circuits this is typically done by taking refrigerant pressure readings at service ports on the liquid and suction sides of the circuit, determining the ambient temperature adjacent the service ports, and comparing these ambient temperature and refrigerant pressure readings to data contained on a system charge chart which is provided by the manufacturer of the air conditioning system.
A charge chart of this type typically has outdoor ambient dry bulb temperature lines plotted on a liquid pressure vs. suction pressure graph. To check the system""s refrigerant charge level, the service technician determines the outdoor ambient temperature, and the liquid and suction line pressures, and marks on the chart the point of intersection of the determined liquid and suction pressures. If this intersection point falls below the determined ambient dry bulb temperature line, the technician adds refrigerant to the circuit, and if the intersection point falls above the determined ambient dry bulb temperature line, the technician removes refrigerant from the circuit. The new liquid line/suction line pressure intersection point is then checked against the determined ambient temperature line, and the refrigerant addition or removal step is repeated until the pressure intersection point falls on the ambient pressure line on the charging chart. As an alternative to this charge chart in graph form, the manufacturer may provide this data in tabular form.
Several well known problems, limitations and disadvantages are typically associated with this conventional method of checking and adjusting the refrigerant charge level of an air conditioning system. For example, not every service technician has appropriate instruments, sensors and the like to efficiently carry out this process. Additionally, as conventionally carried out, this process is an iterative one which can be a time consuming and laborious one. Further, a given portion of the air conditioning system may have a number of independent circuits and associated charge charts. This presents the possibility that the technician could utilize the wrong chart, thereby providing a refrigerant circuit with an incorrect charge level. And, of course, the charging chart(s) initially provided by the manufacturer could be lost.
As can readily be seen from the foregoing, a need exists for an improved technique for measuring and adjusting the charge level of an air conditioning system refrigerant circuit that eliminates or at least substantially reduces the above-mentioned problems, limitations and disadvantages commonly associated with conventional techniques for performing these tasks. It is to this need that the present invention is directed.
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, apparatus is provided for determining and, if necessary, adjusting the charge level of an air conditioning system refrigerant circuit.
Representatively, the apparatus comprises a porting portion interconnectable between the circuit and a refrigerant vessel, the porting portion being operative to selectively transfer refrigerant in a variable direction between the circuit and the refrigerant vessel which may be, for example, a refrigerant charging canister or a refrigerant recovery drum. The apparatus further comprises a valve portion for operating the porting structure, and a sensing portion for sensing ambient temperature and circuit refrigerant pressure levels and responsively generating output signals.
The apparatus also comprises a calculator portion for storing identifying and charging data for a plurality of air conditioning systems, receiving the output signals and system identifying data input by an operator indicative of the circuit being tested, and responsively creating a display indicative of whether the circuit being tested is adequately charged, undercharged or overcharged, the display being automatically changeable in response to variation of at least one of the output signals caused by a flow of refrigerant into or out of the circuit via the refrigerant transfer port.
In a preferred embodiment of the present invention, the apparatus is a refrigerant gauge manifold with a built-in charging calculator, and may be easily and quickly used to both determine the sufficiency of the refrigerant charge in the circuit being tested, and to adjust the refrigerant charge, via the manifold, if necessary.
According to various features of the invention, in a preferred embodiment thereof, the porting portion includes a suction port communicatable with a suction line portion of the circuit, a liquid port communicatable with a liquid line portion of the circuit, and a refrigerant transfer port communicatable with a refrigerant canister or a refrigerant recovery drum. The valve portion representatively includes a first valve operative to selectively permit and preclude communication between the suction and refrigerant transfer ports, and a second valve operative to selectively permit and preclude communication between the liquid and refrigerant transfer ports.
The sensing portion is representatively operative to sense ambient dry bulb temperature and the liquid and suction line refrigerant pressures in the circuit, and illustratively includes a first pressure-to-electric transducer operatively coupled between the suction port and the calculator portion, and a second pressure-to-electric transducer operatively coupled between the liquid port and the calculator portion.